As charge-based non-volatile memories, a flash memory as a representative thereof, is gradually approaching its physical limits, a resistive memory, which is very likely to replace the charge-typed non-volatile memories, has been widely studied during the last decade. Compared to other types of non-volatile memories, the resistive memory has the following advantages: simple structure, fast speed, compatibility with existing fabrication techniques for field effect transistors, potential to be further scaled down and multi-value storage.
A conductive filament theory being as a conductive mechanism of the resistive memory has been widely recognized in academia. This theory holds that a resistance change of the resistive memory occurs due to the forming and breaking of a conductive filament in a resistive layer connected to two electrodes at both sides of the resistive layer. That is, oxygen vacancies or metal ions in the resistive layer produced through electro-chemical reactions migrate under an externally applied electric field, so that a conductive filament is formed. When the conductive filament is formed and thus is connected to the two electrodes, the resistive memory enters into a low resistance state. On the other hand, when the filament is affected thermally or under a reverse electric field, it may break partially or even completely and thus the resistive memory enters into a high resistance state. However, numerous key parameters of the resistive material fluctuate greatly due to the randomness of the forming and breaking of the conductive filament. Such fluctuation significantly degrades the stability and reliability of the operation of the resistive memory and at the same time increases the complexity of peripheral circuits, which becomes a serious obstacle in practical applications.